This invention relates to a recombinant DNA molecule comprising the Streptomyces gal operon.
Hodgson, J. Gen. Micro., 128, 2417-2430 (1982), report that Streptomyces coelicolor A3(2) has a glucose repression system which allows repression at the level of transcription of the arabinose uptake system, one of the glycerol uptake systems, and also repression of the galactose uptake system in wild type strains. There is no report in Hodgson of actual galactose metabolism by S. coelicolor A3(2).
Okeda et at. Mol. Gen. Genet, 196, 501-507 (1984), report that glucose kinase activity, 2-deoxyglu-cose-sensitivy, glucose utilization and glucose repression were all restored to S. coelicolor A3(2) glk (glucose kinase) mutants transformed by a 3.5 kb DNA fragment which contained the glk gene cloned from S. coelicolor into a phage vector.
Seno et at., Mol. Gen. Genet., 193, 119-128 (1984), report the glycerol (gyl) operon of Streptomyces coelicolor, and state that such operon is substrate-inducible and catabolite-repressible.
Debouck et al., Nuc. Acids. Res., 13(6), 1841-1853 (1985), report that the gal operon of E. coli consists of three structurally contiguous genes: which specify the enzymes required for the metabolism of galactose, i.e., galE (uridine diphosphogalactose-4-epimerase), galT (galactose-1-phosphate uridyltransferase) and galK (galactokinase); that such genes are expressed from a polycistronic mRNA in the order E, T, K; that the expression of the promoter distal gene of the operon, galK, is known to be coupled translationally to the galT gene immediately preceding it; that such translational coupling results from a structural overlap between the end of the gait coding sequence and the ribosome binding region of galK; and that the translational coupling of galT and galK ensures the coordinate expression of these genes during the metabolism of galactose.